Question [Q] Downloaded youtube vids

FIRST. TIME. POSTING.
Ok hello! I am new and overly, overwhelmed with my device.. but this is another day,book,life lol, etc.
My main focus for this thread is i have installed the firefox os on my glxyS5.. i got the flashvideodwnldr for it also.. i fin ally figured out how to use it. Too many clicks and taps in my opinion but its doing just what i wish.. however im not rooted BOOOO!!! and again "overwhelmed". I hqve music app,video app, and play music app that was unboxed and factory installed. Also this is a verizon phone. I download songs and everytime i wanna repeat said song i have to get the phone and start it over. ?? what can i do to make this song repeat until the cows come home?? I have tried moving the file as well as copy paste into everything i can think of. Sorry so long felt it was necessary...